Guitar and Audio technology blog

Sunday, 16 January 2011

Amplitude dependent wave shaping

One of the key characteristics of the amplifier even at peak distortion is the effect of input amplitude on the amount of distortion generated.  When playing softly even at full volume, even though there is an increase in overall volume/loudness there is less distortion than when playing harder.  It is important to incorporate this into my chebyshev waveshaping functions as the plug-in should only apply more distortion to higher input values.  A test has been produced separating the input into above and below 0.5 && -0.5 only applying the distortion polynomials above these values.  This works quite well however more subtlety is needed and is currently being developed. 


After some experimentation I have now got a working amplitude dependant distortion waveshaper using chebyshev polynomials.  The code looks at the amplitude level and depending on the number adds specific polynomials too the output variable.  The only problem is that it is extremely computationally excessive and needs to be tested on another pc to establish what the problem is.  I have a feeling as the amplitude changes so often there are too many process leading to too much distortion and sometimes crashing.  I am currently in the process of updating this as well as including a control on the amount of distortion in general.  

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